Good morning!
I agree with both T Dan and Fierlin 1182; however, due to setup restrictions, I introduced 1-week-old chicks into the coop with 2-month0old girls, and kept a very close watch on them for several hours, then several days. To my surprise - and welcome amazement - the olde girls immediately became caretakers and guardians, bunching together as the evening came on to help keep the babies warm, and grouping together when I entered the coop, protecting the babies from the giant human!
Unfortunately, I had to remove the kids from the coop about a week into it, due to very inclement weather - minor cold front (got down in the low-to-mid 60s at night) - and extremely hard downpours with accompnaying winds. The heat lamp bulb got too wet and went out in the middle of the night, and I lost 2 babies - they were soaked and cold to the touch. I brought the other 7 babies inside to the comfort of the utility room - in a box - and they're all fine. They've been inside for about a week, and have grown larger and they're feathering as they should. The weather has straightened out, and the babies are noticeably cramped - guess they got used to having room in the coop right quick! So I'm going to reintroduce them to the girls, probably this morning, and watch them very c,osely again to make sure all is well.
Point I should make: this is not the recommended or "normal" way of doing things, but this is also the first time I've brought chicks inside for any reason. My first flock a few years ago did fine in the coop from a couple of days old with a heat lamp in the coop, and a large overturned box for shelter. I'm not nearly as concerned about the Spring temps - except for the dang cold front that came in with rain - I'm more concerned about the older girls accepting the babies.
So, find what works for you and your flock - just keep a very close eye on reactions from exiting birds when introducing new ones - and remove them immediately if you see pecking going on, especially if you see evidence of blood on the younger/newer birds!
Good luck with your venture - it's a lot of fun! Have a great day, and God bless!